Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2486 insertions, 0 deletions

diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
new file mode 100644
index 0000000000..e855b8fde7
--- /dev/null
+++ b/fs/jfs/jfs_logmgr.c
@@ -0,0 +1,2486 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   Copyright (C) International Business Machines Corp., 2000-2004
+ *   Portions Copyright (C) Christoph Hellwig, 2001-2002
+ */
+
+/*
+ *	jfs_logmgr.c: log manager
+ *
+ * for related information, see transaction manager (jfs_txnmgr.c), and
+ * recovery manager (jfs_logredo.c).
+ *
+ * note: for detail, RTFS.
+ *
+ *	log buffer manager:
+ * special purpose buffer manager supporting log i/o requirements.
+ * per log serial pageout of logpage
+ * queuing i/o requests and redrive i/o at iodone
+ * maintain current logpage buffer
+ * no caching since append only
+ * appropriate jfs buffer cache buffers as needed
+ *
+ *	group commit:
+ * transactions which wrote COMMIT records in the same in-memory
+ * log page during the pageout of previous/current log page(s) are
+ * committed together by the pageout of the page.
+ *
+ *	TBD lazy commit:
+ * transactions are committed asynchronously when the log page
+ * containing it COMMIT is paged out when it becomes full;
+ *
+ *	serialization:
+ * . a per log lock serialize log write.
+ * . a per log lock serialize group commit.
+ * . a per log lock serialize log open/close;
+ *
+ *	TBD log integrity:
+ * careful-write (ping-pong) of last logpage to recover from crash
+ * in overwrite.
+ * detection of split (out-of-order) write of physical sectors
+ * of last logpage via timestamp at end of each sector
+ * with its mirror data array at trailer).
+ *
+ *	alternatives:
+ * lsn - 64-bit monotonically increasing integer vs
+ * 32-bit lspn and page eor.
+ */
+
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/kthread.h>
+#include <linux/buffer_head.h>		/* for sync_blockdev() */
+#include <linux/bio.h>
+#include <linux/freezer.h>
+#include <linux/export.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include "jfs_incore.h"
+#include "jfs_filsys.h"
+#include "jfs_metapage.h"
+#include "jfs_superblock.h"
+#include "jfs_txnmgr.h"
+#include "jfs_debug.h"
+
+
+/*
+ * lbuf's ready to be redriven.  Protected by log_redrive_lock (jfsIO thread)
+ */
+static struct lbuf *log_redrive_list;
+static DEFINE_SPINLOCK(log_redrive_lock);
+
+
+/*
+ *	log read/write serialization (per log)
+ */
+#define LOG_LOCK_INIT(log)	mutex_init(&(log)->loglock)
+#define LOG_LOCK(log)		mutex_lock(&((log)->loglock))
+#define LOG_UNLOCK(log)		mutex_unlock(&((log)->loglock))
+
+
+/*
+ *	log group commit serialization (per log)
+ */
+
+#define LOGGC_LOCK_INIT(log)	spin_lock_init(&(log)->gclock)
+#define LOGGC_LOCK(log)		spin_lock_irq(&(log)->gclock)
+#define LOGGC_UNLOCK(log)	spin_unlock_irq(&(log)->gclock)
+#define LOGGC_WAKEUP(tblk)	wake_up_all(&(tblk)->gcwait)
+
+/*
+ *	log sync serialization (per log)
+ */
+#define	LOGSYNC_DELTA(logsize)		min((logsize)/8, 128*LOGPSIZE)
+#define	LOGSYNC_BARRIER(logsize)	((logsize)/4)
+/*
+#define	LOGSYNC_DELTA(logsize)		min((logsize)/4, 256*LOGPSIZE)
+#define	LOGSYNC_BARRIER(logsize)	((logsize)/2)
+*/
+
+
+/*
+ *	log buffer cache synchronization
+ */
+static DEFINE_SPINLOCK(jfsLCacheLock);
+
+#define	LCACHE_LOCK(flags)	spin_lock_irqsave(&jfsLCacheLock, flags)
+#define	LCACHE_UNLOCK(flags)	spin_unlock_irqrestore(&jfsLCacheLock, flags)
+
+/*
+ * See __SLEEP_COND in jfs_locks.h
+ */
+#define LCACHE_SLEEP_COND(wq, cond, flags)	\
+do {						\
+	if (cond)				\
+		break;				\
+	__SLEEP_COND(wq, cond, LCACHE_LOCK(flags), LCACHE_UNLOCK(flags)); \
+} while (0)
+
+#define	LCACHE_WAKEUP(event)	wake_up(event)
+
+
+/*
+ *	lbuf buffer cache (lCache) control
+ */
+/* log buffer manager pageout control (cumulative, inclusive) */
+#define	lbmREAD		0x0001
+#define	lbmWRITE	0x0002	/* enqueue at tail of write queue;
+				 * init pageout if at head of queue;
+				 */
+#define	lbmRELEASE	0x0004	/* remove from write queue
+				 * at completion of pageout;
+				 * do not free/recycle it yet:
+				 * caller will free it;
+				 */
+#define	lbmSYNC		0x0008	/* do not return to freelist
+				 * when removed from write queue;
+				 */
+#define lbmFREE		0x0010	/* return to freelist
+				 * at completion of pageout;
+				 * the buffer may be recycled;
+				 */
+#define	lbmDONE		0x0020
+#define	lbmERROR	0x0040
+#define lbmGC		0x0080	/* lbmIODone to perform post-GC processing
+				 * of log page
+				 */
+#define lbmDIRECT	0x0100
+
+/*
+ * Global list of active external journals
+ */
+static LIST_HEAD(jfs_external_logs);
+static struct jfs_log *dummy_log;
+static DEFINE_MUTEX(jfs_log_mutex);
+
+/*
+ * forward references
+ */
+static int lmWriteRecord(struct jfs_log * log, struct tblock * tblk,
+			 struct lrd * lrd, struct tlock * tlck);
+
+static int lmNextPage(struct jfs_log * log);
+static int lmLogFileSystem(struct jfs_log * log, struct jfs_sb_info *sbi,
+			   int activate);
+
+static int open_inline_log(struct super_block *sb);
+static int open_dummy_log(struct super_block *sb);
+static int lbmLogInit(struct jfs_log * log);
+static void lbmLogShutdown(struct jfs_log * log);
+static struct lbuf *lbmAllocate(struct jfs_log * log, int);
+static void lbmFree(struct lbuf * bp);
+static void lbmfree(struct lbuf * bp);
+static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp);
+static void lbmWrite(struct jfs_log * log, struct lbuf * bp, int flag, int cant_block);
+static void lbmDirectWrite(struct jfs_log * log, struct lbuf * bp, int flag);
+static int lbmIOWait(struct lbuf * bp, int flag);
+static bio_end_io_t lbmIODone;
+static void lbmStartIO(struct lbuf * bp);
+static void lmGCwrite(struct jfs_log * log, int cant_block);
+static int lmLogSync(struct jfs_log * log, int hard_sync);
+
+
+
+/*
+ *	statistics
+ */
+#ifdef CONFIG_JFS_STATISTICS
+static struct lmStat {
+	uint commit;		/* # of commit */
+	uint pagedone;		/* # of page written */
+	uint submitted;		/* # of pages submitted */
+	uint full_page;		/* # of full pages submitted */
+	uint partial_page;	/* # of partial pages submitted */
+} lmStat;
+#endif
+
+static void write_special_inodes(struct jfs_log *log,
+				 int (*writer)(struct address_space *))
+{
+	struct jfs_sb_info *sbi;
+
+	list_for_each_entry(sbi, &log->sb_list, log_list) {
+		writer(sbi->ipbmap->i_mapping);
+		writer(sbi->ipimap->i_mapping);
+		writer(sbi->direct_inode->i_mapping);
+	}
+}
+
+/*
+ * NAME:	lmLog()
+ *
+ * FUNCTION:	write a log record;
+ *
+ * PARAMETER:
+ *
+ * RETURN:	lsn - offset to the next log record to write (end-of-log);
+ *		-1  - error;
+ *
+ * note: todo: log error handler
+ */
+int lmLog(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
+	  struct tlock * tlck)
+{
+	int lsn;
+	int diffp, difft;
+	struct metapage *mp = NULL;
+	unsigned long flags;
+
+	jfs_info("lmLog: log:0x%p tblk:0x%p, lrd:0x%p tlck:0x%p",
+		 log, tblk, lrd, tlck);
+
+	LOG_LOCK(log);
+
+	/* log by (out-of-transaction) JFS ? */
+	if (tblk == NULL)
+		goto writeRecord;
+
+	/* log from page ? */
+	if (tlck == NULL ||
+	    tlck->type & tlckBTROOT || (mp = tlck->mp) == NULL)
+		goto writeRecord;
+
+	/*
+	 *	initialize/update page/transaction recovery lsn
+	 */
+	lsn = log->lsn;
+
+	LOGSYNC_LOCK(log, flags);
+
+	/*
+	 * initialize page lsn if first log write of the page
+	 */
+	if (mp->lsn == 0) {
+		mp->log = log;
+		mp->lsn = lsn;
+		log->count++;
+
+		/* insert page at tail of logsynclist */
+		list_add_tail(&mp->synclist, &log->synclist);
+	}
+
+	/*
+	 *	initialize/update lsn of tblock of the page
+	 *
+	 * transaction inherits oldest lsn of pages associated
+	 * with allocation/deallocation of resources (their
+	 * log records are used to reconstruct allocation map
+	 * at recovery time: inode for inode allocation map,
+	 * B+-tree index of extent descriptors for block
+	 * allocation map);
+	 * allocation map pages inherit transaction lsn at
+	 * commit time to allow forwarding log syncpt past log
+	 * records associated with allocation/deallocation of
+	 * resources only after persistent map of these map pages
+	 * have been updated and propagated to home.
+	 */
+	/*
+	 * initialize transaction lsn:
+	 */
+	if (tblk->lsn == 0) {
+		/* inherit lsn of its first page logged */
+		tblk->lsn = mp->lsn;
+		log->count++;
+
+		/* insert tblock after the page on logsynclist */
+		list_add(&tblk->synclist, &mp->synclist);
+	}
+	/*
+	 * update transaction lsn:
+	 */
+	else {
+		/* inherit oldest/smallest lsn of page */
+		logdiff(diffp, mp->lsn, log);
+		logdiff(difft, tblk->lsn, log);
+		if (diffp < difft) {
+			/* update tblock lsn with page lsn */
+			tblk->lsn = mp->lsn;
+
+			/* move tblock after page on logsynclist */
+			list_move(&tblk->synclist, &mp->synclist);
+		}
+	}
+
+	LOGSYNC_UNLOCK(log, flags);
+
+	/*
+	 *	write the log record
+	 */
+      writeRecord:
+	lsn = lmWriteRecord(log, tblk, lrd, tlck);
+
+	/*
+	 * forward log syncpt if log reached next syncpt trigger
+	 */
+	logdiff(diffp, lsn, log);
+	if (diffp >= log->nextsync)
+		lsn = lmLogSync(log, 0);
+
+	/* update end-of-log lsn */
+	log->lsn = lsn;
+
+	LOG_UNLOCK(log);
+
+	/* return end-of-log address */
+	return lsn;
+}
+
+/*
+ * NAME:	lmWriteRecord()
+ *
+ * FUNCTION:	move the log record to current log page
+ *
+ * PARAMETER:	cd	- commit descriptor
+ *
+ * RETURN:	end-of-log address
+ *
+ * serialization: LOG_LOCK() held on entry/exit
+ */
+static int
+lmWriteRecord(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
+	      struct tlock * tlck)
+{
+	int lsn = 0;		/* end-of-log address */
+	struct lbuf *bp;	/* dst log page buffer */
+	struct logpage *lp;	/* dst log page */
+	caddr_t dst;		/* destination address in log page */
+	int dstoffset;		/* end-of-log offset in log page */
+	int freespace;		/* free space in log page */
+	caddr_t p;		/* src meta-data page */
+	caddr_t src;
+	int srclen;
+	int nbytes;		/* number of bytes to move */
+	int i;
+	int len;
+	struct linelock *linelock;
+	struct lv *lv;
+	struct lvd *lvd;
+	int l2linesize;
+
+	len = 0;
+
+	/* retrieve destination log page to write */
+	bp = (struct lbuf *) log->bp;
+	lp = (struct logpage *) bp->l_ldata;
+	dstoffset = log->eor;
+
+	/* any log data to write ? */
+	if (tlck == NULL)
+		goto moveLrd;
+
+	/*
+	 *	move log record data
+	 */
+	/* retrieve source meta-data page to log */
+	if (tlck->flag & tlckPAGELOCK) {
+		p = (caddr_t) (tlck->mp->data);
+		linelock = (struct linelock *) & tlck->lock;
+	}
+	/* retrieve source in-memory inode to log */
+	else if (tlck->flag & tlckINODELOCK) {
+		if (tlck->type & tlckDTREE)
+			p = (caddr_t) &JFS_IP(tlck->ip)->i_dtroot;
+		else
+			p = (caddr_t) &JFS_IP(tlck->ip)->i_xtroot;
+		linelock = (struct linelock *) & tlck->lock;
+	}
+	else {
+		jfs_err("lmWriteRecord: UFO tlck:0x%p", tlck);
+		return 0;	/* Probably should trap */
+	}
+	l2linesize = linelock->l2linesize;
+
+      moveData:
+	ASSERT(linelock->index <= linelock->maxcnt);
+
+	lv = linelock->lv;
+	for (i = 0; i < linelock->index; i++, lv++) {
+		if (lv->length == 0)
+			continue;
+
+		/* is page full ? */
+		if (dstoffset >= LOGPSIZE - LOGPTLRSIZE) {
+			/* page become full: move on to next page */
+			lmNextPage(log);
+
+			bp = log->bp;
+			lp = (struct logpage *) bp->l_ldata;
+			dstoffset = LOGPHDRSIZE;
+		}
+
+		/*
+		 * move log vector data
+		 */
+		src = (u8 *) p + (lv->offset << l2linesize);
+		srclen = lv->length << l2linesize;
+		len += srclen;
+		while (srclen > 0) {
+			freespace = (LOGPSIZE - LOGPTLRSIZE) - dstoffset;
+			nbytes = min(freespace, srclen);
+			dst = (caddr_t) lp + dstoffset;
+			memcpy(dst, src, nbytes);
+			dstoffset += nbytes;
+
+			/* is page not full ? */
+			if (dstoffset < LOGPSIZE - LOGPTLRSIZE)
+				break;
+
+			/* page become full: move on to next page */
+			lmNextPage(log);
+
+			bp = (struct lbuf *) log->bp;
+			lp = (struct logpage *) bp->l_ldata;
+			dstoffset = LOGPHDRSIZE;
+
+			srclen -= nbytes;
+			src += nbytes;
+		}
+
+		/*
+		 * move log vector descriptor
+		 */
+		len += 4;
+		lvd = (struct lvd *) ((caddr_t) lp + dstoffset);
+		lvd->offset = cpu_to_le16(lv->offset);
+		lvd->length = cpu_to_le16(lv->length);
+		dstoffset += 4;
+		jfs_info("lmWriteRecord: lv offset:%d length:%d",
+			 lv->offset, lv->length);
+	}
+
+	if ((i = linelock->next)) {
+		linelock = (struct linelock *) lid_to_tlock(i);
+		goto moveData;
+	}
+
+	/*
+	 *	move log record descriptor
+	 */
+      moveLrd:
+	lrd->length = cpu_to_le16(len);
+
+	src = (caddr_t) lrd;
+	srclen = LOGRDSIZE;
+
+	while (srclen > 0) {
+		freespace = (LOGPSIZE - LOGPTLRSIZE) - dstoffset;
+		nbytes = min(freespace, srclen);
+		dst = (caddr_t) lp + dstoffset;
+		memcpy(dst, src, nbytes);
+
+		dstoffset += nbytes;
+		srclen -= nbytes;
+
+		/* are there more to move than freespace of page ? */
+		if (srclen)
+			goto pageFull;
+
+		/*
+		 * end of log record descriptor
+		 */
+
+		/* update last log record eor */
+		log->eor = dstoffset;
+		bp->l_eor = dstoffset;
+		lsn = (log->page << L2LOGPSIZE) + dstoffset;
+
+		if (lrd->type & cpu_to_le16(LOG_COMMIT)) {
+			tblk->clsn = lsn;
+			jfs_info("wr: tclsn:0x%x, beor:0x%x", tblk->clsn,
+				 bp->l_eor);
+
+			INCREMENT(lmStat.commit);	/* # of commit */
+
+			/*
+			 * enqueue tblock for group commit:
+			 *
+			 * enqueue tblock of non-trivial/synchronous COMMIT
+			 * at tail of group commit queue
+			 * (trivial/asynchronous COMMITs are ignored by
+			 * group commit.)
+			 */
+			LOGGC_LOCK(log);
+
+			/* init tblock gc state */
+			tblk->flag = tblkGC_QUEUE;
+			tblk->bp = log->bp;
+			tblk->pn = log->page;
+			tblk->eor = log->eor;
+
+			/* enqueue transaction to commit queue */
+			list_add_tail(&tblk->cqueue, &log->cqueue);
+
+			LOGGC_UNLOCK(log);
+		}
+
+		jfs_info("lmWriteRecord: lrd:0x%04x bp:0x%p pn:%d eor:0x%x",
+			le16_to_cpu(lrd->type), log->bp, log->page, dstoffset);
+
+		/* page not full ? */
+		if (dstoffset < LOGPSIZE - LOGPTLRSIZE)
+			return lsn;
+
+	      pageFull:
+		/* page become full: move on to next page */
+		lmNextPage(log);
+
+		bp = (struct lbuf *) log->bp;
+		lp = (struct logpage *) bp->l_ldata;
+		dstoffset = LOGPHDRSIZE;
+		src += nbytes;
+	}
+
+	return lsn;
+}
+
+
+/*
+ * NAME:	lmNextPage()
+ *
+ * FUNCTION:	write current page and allocate next page.
+ *
+ * PARAMETER:	log
+ *
+ * RETURN:	0
+ *
+ * serialization: LOG_LOCK() held on entry/exit
+ */
+static int lmNextPage(struct jfs_log * log)
+{
+	struct logpage *lp;
+	int lspn;		/* log sequence page number */
+	int pn;			/* current page number */
+	struct lbuf *bp;
+	struct lbuf *nextbp;
+	struct tblock *tblk;
+
+	/* get current log page number and log sequence page number */
+	pn = log->page;
+	bp = log->bp;
+	lp = (struct logpage *) bp->l_ldata;
+	lspn = le32_to_cpu(lp->h.page);
+
+	LOGGC_LOCK(log);
+
+	/*
+	 *	write or queue the full page at the tail of write queue
+	 */
+	/* get the tail tblk on commit queue */
+	if (list_empty(&log->cqueue))
+		tblk = NULL;
+	else
+		tblk = list_entry(log->cqueue.prev, struct tblock, cqueue);
+
+	/* every tblk who has COMMIT record on the current page,
+	 * and has not been committed, must be on commit queue
+	 * since tblk is queued at commit queueu at the time
+	 * of writing its COMMIT record on the page before
+	 * page becomes full (even though the tblk thread
+	 * who wrote COMMIT record may have been suspended
+	 * currently);
+	 */
+
+	/* is page bound with outstanding tail tblk ? */
+	if (tblk && tblk->pn == pn) {
+		/* mark tblk for end-of-page */
+		tblk->flag |= tblkGC_EOP;
+
+		if (log->cflag & logGC_PAGEOUT) {
+			/* if page is not already on write queue,
+			 * just enqueue (no lbmWRITE to prevent redrive)
+			 * buffer to wqueue to ensure correct serial order
+			 * of the pages since log pages will be added
+			 * continuously
+			 */
+			if (bp->l_wqnext == NULL)
+				lbmWrite(log, bp, 0, 0);
+		} else {
+			/*
+			 * No current GC leader, initiate group commit
+			 */
+			log->cflag |= logGC_PAGEOUT;
+			lmGCwrite(log, 0);
+		}
+	}
+	/* page is not bound with outstanding tblk:
+	 * init write or mark it to be redriven (lbmWRITE)
+	 */
+	else {
+		/* finalize the page */
+		bp->l_ceor = bp->l_eor;
+		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_ceor);
+		lbmWrite(log, bp, lbmWRITE | lbmRELEASE | lbmFREE, 0);
+	}
+	LOGGC_UNLOCK(log);
+
+	/*
+	 *	allocate/initialize next page
+	 */
+	/* if log wraps, the first data page of log is 2
+	 * (0 never used, 1 is superblock).
+	 */
+	log->page = (pn == log->size - 1) ? 2 : pn + 1;
+	log->eor = LOGPHDRSIZE;	/* ? valid page empty/full at logRedo() */
+
+	/* allocate/initialize next log page buffer */
+	nextbp = lbmAllocate(log, log->page);
+	nextbp->l_eor = log->eor;
+	log->bp = nextbp;
+
+	/* initialize next log page */
+	lp = (struct logpage *) nextbp->l_ldata;
+	lp->h.page = lp->t.page = cpu_to_le32(lspn + 1);
+	lp->h.eor = lp->t.eor = cpu_to_le16(LOGPHDRSIZE);
+
+	return 0;
+}
+
+
+/*
+ * NAME:	lmGroupCommit()
+ *
+ * FUNCTION:	group commit
+ *	initiate pageout of the pages with COMMIT in the order of
+ *	page number - redrive pageout of the page at the head of
+ *	pageout queue until full page has been written.
+ *
+ * RETURN:
+ *
+ * NOTE:
+ *	LOGGC_LOCK serializes log group commit queue, and
+ *	transaction blocks on the commit queue.
+ *	N.B. LOG_LOCK is NOT held during lmGroupCommit().
+ */
+int lmGroupCommit(struct jfs_log * log, struct tblock * tblk)
+{
+	int rc = 0;
+
+	LOGGC_LOCK(log);
+
+	/* group committed already ? */
+	if (tblk->flag & tblkGC_COMMITTED) {
+		if (tblk->flag & tblkGC_ERROR)
+			rc = -EIO;
+
+		LOGGC_UNLOCK(log);
+		return rc;
+	}
+	jfs_info("lmGroup Commit: tblk = 0x%p, gcrtc = %d", tblk, log->gcrtc);
+
+	if (tblk->xflag & COMMIT_LAZY)
+		tblk->flag |= tblkGC_LAZY;
+
+	if ((!(log->cflag & logGC_PAGEOUT)) && (!list_empty(&log->cqueue)) &&
+	    (!(tblk->xflag & COMMIT_LAZY) || test_bit(log_FLUSH, &log->flag)
+	     || jfs_tlocks_low)) {
+		/*
+		 * No pageout in progress
+		 *
+		 * start group commit as its group leader.
+		 */
+		log->cflag |= logGC_PAGEOUT;
+
+		lmGCwrite(log, 0);
+	}
+
+	if (tblk->xflag & COMMIT_LAZY) {
+		/*
+		 * Lazy transactions can leave now
+		 */
+		LOGGC_UNLOCK(log);
+		return 0;
+	}
+
+	/* lmGCwrite gives up LOGGC_LOCK, check again */
+
+	if (tblk->flag & tblkGC_COMMITTED) {
+		if (tblk->flag & tblkGC_ERROR)
+			rc = -EIO;
+
+		LOGGC_UNLOCK(log);
+		return rc;
+	}
+
+	/* upcount transaction waiting for completion
+	 */
+	log->gcrtc++;
+	tblk->flag |= tblkGC_READY;
+
+	__SLEEP_COND(tblk->gcwait, (tblk->flag & tblkGC_COMMITTED),
+		     LOGGC_LOCK(log), LOGGC_UNLOCK(log));
+
+	/* removed from commit queue */
+	if (tblk->flag & tblkGC_ERROR)
+		rc = -EIO;
+
+	LOGGC_UNLOCK(log);
+	return rc;
+}
+
+/*
+ * NAME:	lmGCwrite()
+ *
+ * FUNCTION:	group commit write
+ *	initiate write of log page, building a group of all transactions
+ *	with commit records on that page.
+ *
+ * RETURN:	None
+ *
+ * NOTE:
+ *	LOGGC_LOCK must be held by caller.
+ *	N.B. LOG_LOCK is NOT held during lmGroupCommit().
+ */
+static void lmGCwrite(struct jfs_log * log, int cant_write)
+{
+	struct lbuf *bp;
+	struct logpage *lp;
+	int gcpn;		/* group commit page number */
+	struct tblock *tblk;
+	struct tblock *xtblk = NULL;
+
+	/*
+	 * build the commit group of a log page
+	 *
+	 * scan commit queue and make a commit group of all
+	 * transactions with COMMIT records on the same log page.
+	 */
+	/* get the head tblk on the commit queue */
+	gcpn = list_entry(log->cqueue.next, struct tblock, cqueue)->pn;
+
+	list_for_each_entry(tblk, &log->cqueue, cqueue) {
+		if (tblk->pn != gcpn)
+			break;
+
+		xtblk = tblk;
+
+		/* state transition: (QUEUE, READY) -> COMMIT */
+		tblk->flag |= tblkGC_COMMIT;
+	}
+	tblk = xtblk;		/* last tblk of the page */
+
+	/*
+	 * pageout to commit transactions on the log page.
+	 */
+	bp = (struct lbuf *) tblk->bp;
+	lp = (struct logpage *) bp->l_ldata;
+	/* is page already full ? */
+	if (tblk->flag & tblkGC_EOP) {
+		/* mark page to free at end of group commit of the page */
+		tblk->flag &= ~tblkGC_EOP;
+		tblk->flag |= tblkGC_FREE;
+		bp->l_ceor = bp->l_eor;
+		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_ceor);
+		lbmWrite(log, bp, lbmWRITE | lbmRELEASE | lbmGC,
+			 cant_write);
+		INCREMENT(lmStat.full_page);
+	}
+	/* page is not yet full */
+	else {
+		bp->l_ceor = tblk->eor;	/* ? bp->l_ceor = bp->l_eor; */
+		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_ceor);
+		lbmWrite(log, bp, lbmWRITE | lbmGC, cant_write);
+		INCREMENT(lmStat.partial_page);
+	}
+}
+
+/*
+ * NAME:	lmPostGC()
+ *
+ * FUNCTION:	group commit post-processing
+ *	Processes transactions after their commit records have been written
+ *	to disk, redriving log I/O if necessary.
+ *
+ * RETURN:	None
+ *
+ * NOTE:
+ *	This routine is called a interrupt time by lbmIODone
+ */
+static void lmPostGC(struct lbuf * bp)
+{
+	unsigned long flags;
+	struct jfs_log *log = bp->l_log;
+	struct logpage *lp;
+	struct tblock *tblk, *temp;
+
+	//LOGGC_LOCK(log);
+	spin_lock_irqsave(&log->gclock, flags);
+	/*
+	 * current pageout of group commit completed.
+	 *
+	 * remove/wakeup transactions from commit queue who were
+	 * group committed with the current log page
+	 */
+	list_for_each_entry_safe(tblk, temp, &log->cqueue, cqueue) {
+		if (!(tblk->flag & tblkGC_COMMIT))
+			break;
+		/* if transaction was marked GC_COMMIT then
+		 * it has been shipped in the current pageout
+		 * and made it to disk - it is committed.
+		 */
+
+		if (bp->l_flag & lbmERROR)
+			tblk->flag |= tblkGC_ERROR;
+
+		/* remove it from the commit queue */
+		list_del(&tblk->cqueue);
+		tblk->flag &= ~tblkGC_QUEUE;
+
+		if (tblk == log->flush_tblk) {
+			/* we can stop flushing the log now */
+			clear_bit(log_FLUSH, &log->flag);
+			log->flush_tblk = NULL;
+		}
+
+		jfs_info("lmPostGC: tblk = 0x%p, flag = 0x%x", tblk,
+			 tblk->flag);
+
+		if (!(tblk->xflag & COMMIT_FORCE))
+			/*
+			 * Hand tblk over to lazy commit thread
+			 */
+			txLazyUnlock(tblk);
+		else {
+			/* state transition: COMMIT -> COMMITTED */
+			tblk->flag |= tblkGC_COMMITTED;
+
+			if (tblk->flag & tblkGC_READY)
+				log->gcrtc--;
+
+			LOGGC_WAKEUP(tblk);
+		}
+
+		/* was page full before pageout ?
+		 * (and this is the last tblk bound with the page)
+		 */
+		if (tblk->flag & tblkGC_FREE)
+			lbmFree(bp);
+		/* did page become full after pageout ?
+		 * (and this is the last tblk bound with the page)
+		 */
+		else if (tblk->flag & tblkGC_EOP) {
+			/* finalize the page */
+			lp = (struct logpage *) bp->l_ldata;
+			bp->l_ceor = bp->l_eor;
+			lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_eor);
+			jfs_info("lmPostGC: calling lbmWrite");
+			lbmWrite(log, bp, lbmWRITE | lbmRELEASE | lbmFREE,
+				 1);
+		}
+
+	}
+
+	/* are there any transactions who have entered lnGroupCommit()
+	 * (whose COMMITs are after that of the last log page written.
+	 * They are waiting for new group commit (above at (SLEEP 1))
+	 * or lazy transactions are on a full (queued) log page,
+	 * select the latest ready transaction as new group leader and
+	 * wake her up to lead her group.
+	 */
+	if ((!list_empty(&log->cqueue)) &&
+	    ((log->gcrtc > 0) || (tblk->bp->l_wqnext != NULL) ||
+	     test_bit(log_FLUSH, &log->flag) || jfs_tlocks_low))
+		/*
+		 * Call lmGCwrite with new group leader
+		 */
+		lmGCwrite(log, 1);
+
+	/* no transaction are ready yet (transactions are only just
+	 * queued (GC_QUEUE) and not entered for group commit yet).
+	 * the first transaction entering group commit
+	 * will elect herself as new group leader.
+	 */
+	else
+		log->cflag &= ~logGC_PAGEOUT;
+
+	//LOGGC_UNLOCK(log);
+	spin_unlock_irqrestore(&log->gclock, flags);
+	return;
+}
+
+/*
+ * NAME:	lmLogSync()
+ *
+ * FUNCTION:	write log SYNCPT record for specified log
+ *	if new sync address is available
+ *	(normally the case if sync() is executed by back-ground
+ *	process).
+ *	calculate new value of i_nextsync which determines when
+ *	this code is called again.
+ *
+ * PARAMETERS:	log	- log structure
+ *		hard_sync - 1 to force all metadata to be written
+ *
+ * RETURN:	0
+ *
+ * serialization: LOG_LOCK() held on entry/exit
+ */
+static int lmLogSync(struct jfs_log * log, int hard_sync)
+{
+	int logsize;
+	int written;		/* written since last syncpt */
+	int free;		/* free space left available */
+	int delta;		/* additional delta to write normally */
+	int more;		/* additional write granted */
+	struct lrd lrd;
+	int lsn;
+	struct logsyncblk *lp;
+	unsigned long flags;
+
+	/* push dirty metapages out to disk */
+	if (hard_sync)
+		write_special_inodes(log, filemap_fdatawrite);
+	else
+		write_special_inodes(log, filemap_flush);
+
+	/*
+	 *	forward syncpt
+	 */
+	/* if last sync is same as last syncpt,
+	 * invoke sync point forward processing to update sync.
+	 */
+
+	if (log->sync == log->syncpt) {
+		LOGSYNC_LOCK(log, flags);
+		if (list_empty(&log->synclist))
+			log->sync = log->lsn;
+		else {
+			lp = list_entry(log->synclist.next,
+					struct logsyncblk, synclist);
+			log->sync = lp->lsn;
+		}
+		LOGSYNC_UNLOCK(log, flags);
+
+	}
+
+	/* if sync is different from last syncpt,
+	 * write a SYNCPT record with syncpt = sync.
+	 * reset syncpt = sync
+	 */
+	if (log->sync != log->syncpt) {
+		lrd.logtid = 0;
+		lrd.backchain = 0;
+		lrd.type = cpu_to_le16(LOG_SYNCPT);
+		lrd.length = 0;
+		lrd.log.syncpt.sync = cpu_to_le32(log->sync);
+		lsn = lmWriteRecord(log, NULL, &lrd, NULL);
+
+		log->syncpt = log->sync;
+	} else
+		lsn = log->lsn;
+
+	/*
+	 *	setup next syncpt trigger (SWAG)
+	 */
+	logsize = log->logsize;
+
+	logdiff(written, lsn, log);
+	free = logsize - written;
+	delta = LOGSYNC_DELTA(logsize);
+	more = min(free / 2, delta);
+	if (more < 2 * LOGPSIZE) {
+		jfs_warn("\n ... Log Wrap ... Log Wrap ... Log Wrap ...\n");
+		/*
+		 *	log wrapping
+		 *
+		 * option 1 - panic ? No.!
+		 * option 2 - shutdown file systems
+		 *	      associated with log ?
+		 * option 3 - extend log ?
+		 * option 4 - second chance
+		 *
+		 * mark log wrapped, and continue.
+		 * when all active transactions are completed,
+		 * mark log valid for recovery.
+		 * if crashed during invalid state, log state
+		 * implies invalid log, forcing fsck().
+		 */
+		/* mark log state log wrap in log superblock */
+		/* log->state = LOGWRAP; */
+
+		/* reset sync point computation */
+		log->syncpt = log->sync = lsn;
+		log->nextsync = delta;
+	} else
+		/* next syncpt trigger = written + more */
+		log->nextsync = written + more;
+
+	/* if number of bytes written from last sync point is more
+	 * than 1/4 of the log size, stop new transactions from
+	 * starting until all current transactions are completed
+	 * by setting syncbarrier flag.
+	 */
+	if (!test_bit(log_SYNCBARRIER, &log->flag) &&
+	    (written > LOGSYNC_BARRIER(logsize)) && log->active) {
+		set_bit(log_SYNCBARRIER, &log->flag);
+		jfs_info("log barrier on: lsn=0x%x syncpt=0x%x", lsn,
+			 log->syncpt);
+		/*
+		 * We may have to initiate group commit
+		 */
+		jfs_flush_journal(log, 0);
+	}
+
+	return lsn;
+}
+
+/*
+ * NAME:	jfs_syncpt
+ *
+ * FUNCTION:	write log SYNCPT record for specified log
+ *
+ * PARAMETERS:	log	  - log structure
+ *		hard_sync - set to 1 to force metadata to be written
+ */
+void jfs_syncpt(struct jfs_log *log, int hard_sync)
+{	LOG_LOCK(log);
+	if (!test_bit(log_QUIESCE, &log->flag))
+		lmLogSync(log, hard_sync);
+	LOG_UNLOCK(log);
+}
+
+/*
+ * NAME:	lmLogOpen()
+ *
+ * FUNCTION:	open the log on first open;
+ *	insert filesystem in the active list of the log.
+ *
+ * PARAMETER:	ipmnt	- file system mount inode
+ *		iplog	- log inode (out)
+ *
+ * RETURN:
+ *
+ * serialization:
+ */
+int lmLogOpen(struct super_block *sb)
+{
+	int rc;
+	struct block_device *bdev;
+	struct jfs_log *log;
+	struct jfs_sb_info *sbi = JFS_SBI(sb);
+
+	if (sbi->flag & JFS_NOINTEGRITY)
+		return open_dummy_log(sb);
+
+	if (sbi->mntflag & JFS_INLINELOG)
+		return open_inline_log(sb);
+
+	mutex_lock(&jfs_log_mutex);
+	list_for_each_entry(log, &jfs_external_logs, journal_list) {
+		if (log->bdev->bd_dev == sbi->logdev) {
+			if (!uuid_equal(&log->uuid, &sbi->loguuid)) {
+				jfs_warn("wrong uuid on JFS journal");
+				mutex_unlock(&jfs_log_mutex);
+				return -EINVAL;
+			}
+			/*
+			 * add file system to log active file system list
+			 */
+			if ((rc = lmLogFileSystem(log, sbi, 1))) {
+				mutex_unlock(&jfs_log_mutex);
+				return rc;
+			}
+			goto journal_found;
+		}
+	}
+
+	if (!(log = kzalloc(sizeof(struct jfs_log), GFP_KERNEL))) {
+		mutex_unlock(&jfs_log_mutex);
+		return -ENOMEM;
+	}
+	INIT_LIST_HEAD(&log->sb_list);
+	init_waitqueue_head(&log->syncwait);
+
+	/*
+	 *	external log as separate logical volume
+	 *
+	 * file systems to log may have n-to-1 relationship;
+	 */
+
+	bdev = blkdev_get_by_dev(sbi->logdev, BLK_OPEN_READ | BLK_OPEN_WRITE,
+				 log, NULL);
+	if (IS_ERR(bdev)) {
+		rc = PTR_ERR(bdev);
+		goto free;
+	}
+
+	log->bdev = bdev;
+	uuid_copy(&log->uuid, &sbi->loguuid);
+
+	/*
+	 * initialize log:
+	 */
+	if ((rc = lmLogInit(log)))
+		goto close;
+
+	list_add(&log->journal_list, &jfs_external_logs);
+
+	/*
+	 * add file system to log active file system list
+	 */
+	if ((rc = lmLogFileSystem(log, sbi, 1)))
+		goto shutdown;
+
+journal_found:
+	LOG_LOCK(log);
+	list_add(&sbi->log_list, &log->sb_list);
+	sbi->log = log;
+	LOG_UNLOCK(log);
+
+	mutex_unlock(&jfs_log_mutex);
+	return 0;
+
+	/*
+	 *	unwind on error
+	 */
+      shutdown:		/* unwind lbmLogInit() */
+	list_del(&log->journal_list);
+	lbmLogShutdown(log);
+
+      close:		/* close external log device */
+	blkdev_put(bdev, log);
+
+      free:		/* free log descriptor */
+	mutex_unlock(&jfs_log_mutex);
+	kfree(log);
+
+	jfs_warn("lmLogOpen: exit(%d)", rc);
+	return rc;
+}
+
+static int open_inline_log(struct super_block *sb)
+{
+	struct jfs_log *log;
+	int rc;
+
+	if (!(log = kzalloc(sizeof(struct jfs_log), GFP_KERNEL)))
+		return -ENOMEM;
+	INIT_LIST_HEAD(&log->sb_list);
+	init_waitqueue_head(&log->syncwait);
+
+	set_bit(log_INLINELOG, &log->flag);
+	log->bdev = sb->s_bdev;
+	log->base = addressPXD(&JFS_SBI(sb)->logpxd);
+	log->size = lengthPXD(&JFS_SBI(sb)->logpxd) >>
+	    (L2LOGPSIZE - sb->s_blocksize_bits);
+	log->l2bsize = sb->s_blocksize_bits;
+	ASSERT(L2LOGPSIZE >= sb->s_blocksize_bits);
+
+	/*
+	 * initialize log.
+	 */
+	if ((rc = lmLogInit(log))) {
+		kfree(log);
+		jfs_warn("lmLogOpen: exit(%d)", rc);
+		return rc;
+	}
+
+	list_add(&JFS_SBI(sb)->log_list, &log->sb_list);
+	JFS_SBI(sb)->log = log;
+
+	return rc;
+}
+
+static int open_dummy_log(struct super_block *sb)
+{
+	int rc;
+
+	mutex_lock(&jfs_log_mutex);
+	if (!dummy_log) {
+		dummy_log = kzalloc(sizeof(struct jfs_log), GFP_KERNEL);
+		if (!dummy_log) {
+			mutex_unlock(&jfs_log_mutex);
+			return -ENOMEM;
+		}
+		INIT_LIST_HEAD(&dummy_log->sb_list);
+		init_waitqueue_head(&dummy_log->syncwait);
+		dummy_log->no_integrity = 1;
+		/* Make up some stuff */
+		dummy_log->base = 0;
+		dummy_log->size = 1024;
+		rc = lmLogInit(dummy_log);
+		if (rc) {
+			kfree(dummy_log);
+			dummy_log = NULL;
+			mutex_unlock(&jfs_log_mutex);
+			return rc;
+		}
+	}
+
+	LOG_LOCK(dummy_log);
+	list_add(&JFS_SBI(sb)->log_list, &dummy_log->sb_list);
+	JFS_SBI(sb)->log = dummy_log;
+	LOG_UNLOCK(dummy_log);
+	mutex_unlock(&jfs_log_mutex);
+
+	return 0;
+}
+
+/*
+ * NAME:	lmLogInit()
+ *
+ * FUNCTION:	log initialization at first log open.
+ *
+ *	logredo() (or logformat()) should have been run previously.
+ *	initialize the log from log superblock.
+ *	set the log state in the superblock to LOGMOUNT and
+ *	write SYNCPT log record.
+ *
+ * PARAMETER:	log	- log structure
+ *
+ * RETURN:	0	- if ok
+ *		-EINVAL	- bad log magic number or superblock dirty
+ *		error returned from logwait()
+ *
+ * serialization: single first open thread
+ */
+int lmLogInit(struct jfs_log * log)
+{
+	int rc = 0;
+	struct lrd lrd;
+	struct logsuper *logsuper;
+	struct lbuf *bpsuper;
+	struct lbuf *bp;
+	struct logpage *lp;
+	int lsn = 0;
+
+	jfs_info("lmLogInit: log:0x%p", log);
+
+	/* initialize the group commit serialization lock */
+	LOGGC_LOCK_INIT(log);
+
+	/* allocate/initialize the log write serialization lock */
+	LOG_LOCK_INIT(log);
+
+	LOGSYNC_LOCK_INIT(log);
+
+	INIT_LIST_HEAD(&log->synclist);
+
+	INIT_LIST_HEAD(&log->cqueue);
+	log->flush_tblk = NULL;
+
+	log->count = 0;
+
+	/*
+	 * initialize log i/o
+	 */
+	if ((rc = lbmLogInit(log)))
+		return rc;
+
+	if (!test_bit(log_INLINELOG, &log->flag))
+		log->l2bsize = L2LOGPSIZE;
+
+	/* check for disabled journaling to disk */
+	if (log->no_integrity) {
+		/*
+		 * Journal pages will still be filled.  When the time comes
+		 * to actually do the I/O, the write is not done, and the
+		 * endio routine is called directly.
+		 */
+		bp = lbmAllocate(log , 0);
+		log->bp = bp;
+		bp->l_pn = bp->l_eor = 0;
+	} else {
+		/*
+		 * validate log superblock
+		 */
+		if ((rc = lbmRead(log, 1, &bpsuper)))
+			goto errout10;
+
+		logsuper = (struct logsuper *) bpsuper->l_ldata;
+
+		if (logsuper->magic != cpu_to_le32(LOGMAGIC)) {
+			jfs_warn("*** Log Format Error ! ***");
+			rc = -EINVAL;
+			goto errout20;
+		}
+
+		/* logredo() should have been run successfully. */
+		if (logsuper->state != cpu_to_le32(LOGREDONE)) {
+			jfs_warn("*** Log Is Dirty ! ***");
+			rc = -EINVAL;
+			goto errout20;
+		}
+
+		/* initialize log from log superblock */
+		if (test_bit(log_INLINELOG,&log->flag)) {
+			if (log->size != le32_to_cpu(logsuper->size)) {
+				rc = -EINVAL;
+				goto errout20;
+			}
+			jfs_info("lmLogInit: inline log:0x%p base:0x%Lx size:0x%x",
+				 log, (unsigned long long)log->base, log->size);
+		} else {
+			if (!uuid_equal(&logsuper->uuid, &log->uuid)) {
+				jfs_warn("wrong uuid on JFS log device");
+				rc = -EINVAL;
+				goto errout20;
+			}
+			log->size = le32_to_cpu(logsuper->size);
+			log->l2bsize = le32_to_cpu(logsuper->l2bsize);
+			jfs_info("lmLogInit: external log:0x%p base:0x%Lx size:0x%x",
+				 log, (unsigned long long)log->base, log->size);
+		}
+
+		log->page = le32_to_cpu(logsuper->end) / LOGPSIZE;
+		log->eor = le32_to_cpu(logsuper->end) - (LOGPSIZE * log->page);
+
+		/*
+		 * initialize for log append write mode
+		 */
+		/* establish current/end-of-log page/buffer */
+		if ((rc = lbmRead(log, log->page, &bp)))
+			goto errout20;
+
+		lp = (struct logpage *) bp->l_ldata;
+
+		jfs_info("lmLogInit: lsn:0x%x page:%d eor:%d:%d",
+			 le32_to_cpu(logsuper->end), log->page, log->eor,
+			 le16_to_cpu(lp->h.eor));
+
+		log->bp = bp;
+		bp->l_pn = log->page;
+		bp->l_eor = log->eor;
+
+		/* if current page is full, move on to next page */
+		if (log->eor >= LOGPSIZE - LOGPTLRSIZE)
+			lmNextPage(log);
+
+		/*
+		 * initialize log syncpoint
+		 */
+		/*
+		 * write the first SYNCPT record with syncpoint = 0
+		 * (i.e., log redo up to HERE !);
+		 * remove current page from lbm write queue at end of pageout
+		 * (to write log superblock update), but do not release to
+		 * freelist;
+		 */
+		lrd.logtid = 0;
+		lrd.backchain = 0;
+		lrd.type = cpu_to_le16(LOG_SYNCPT);
+		lrd.length = 0;
+		lrd.log.syncpt.sync = 0;
+		lsn = lmWriteRecord(log, NULL, &lrd, NULL);
+		bp = log->bp;
+		bp->l_ceor = bp->l_eor;
+		lp = (struct logpage *) bp->l_ldata;
+		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_eor);
+		lbmWrite(log, bp, lbmWRITE | lbmSYNC, 0);
+		if ((rc = lbmIOWait(bp, 0)))
+			goto errout30;
+
+		/*
+		 * update/write superblock
+		 */
+		logsuper->state = cpu_to_le32(LOGMOUNT);
+		log->serial = le32_to_cpu(logsuper->serial) + 1;
+		logsuper->serial = cpu_to_le32(log->serial);
+		lbmDirectWrite(log, bpsuper, lbmWRITE | lbmRELEASE | lbmSYNC);
+		if ((rc = lbmIOWait(bpsuper, lbmFREE)))
+			goto errout30;
+	}
+
+	/* initialize logsync parameters */
+	log->logsize = (log->size - 2) << L2LOGPSIZE;
+	log->lsn = lsn;
+	log->syncpt = lsn;
+	log->sync = log->syncpt;
+	log->nextsync = LOGSYNC_DELTA(log->logsize);
+
+	jfs_info("lmLogInit: lsn:0x%x syncpt:0x%x sync:0x%x",
+		 log->lsn, log->syncpt, log->sync);
+
+	/*
+	 * initialize for lazy/group commit
+	 */
+	log->clsn = lsn;
+
+	return 0;
+
+	/*
+	 *	unwind on error
+	 */
+      errout30:		/* release log page */
+	log->wqueue = NULL;
+	bp->l_wqnext = NULL;
+	lbmFree(bp);
+
+      errout20:		/* release log superblock */
+	lbmFree(bpsuper);
+
+      errout10:		/* unwind lbmLogInit() */
+	lbmLogShutdown(log);
+
+	jfs_warn("lmLogInit: exit(%d)", rc);
+	return rc;
+}
+
+
+/*
+ * NAME:	lmLogClose()
+ *
+ * FUNCTION:	remove file system <ipmnt> from active list of log <iplog>
+ *		and close it on last close.
+ *
+ * PARAMETER:	sb	- superblock
+ *
+ * RETURN:	errors from subroutines
+ *
+ * serialization:
+ */
+int lmLogClose(struct super_block *sb)
+{
+	struct jfs_sb_info *sbi = JFS_SBI(sb);
+	struct jfs_log *log = sbi->log;
+	struct block_device *bdev;
+	int rc = 0;
+
+	jfs_info("lmLogClose: log:0x%p", log);
+
+	mutex_lock(&jfs_log_mutex);
+	LOG_LOCK(log);
+	list_del(&sbi->log_list);
+	LOG_UNLOCK(log);
+	sbi->log = NULL;
+
+	/*
+	 * We need to make sure all of the "written" metapages
+	 * actually make it to disk
+	 */
+	sync_blockdev(sb->s_bdev);
+
+	if (test_bit(log_INLINELOG, &log->flag)) {
+		/*
+		 *	in-line log in host file system
+		 */
+		rc = lmLogShutdown(log);
+		kfree(log);
+		goto out;
+	}
+
+	if (!log->no_integrity)
+		lmLogFileSystem(log, sbi, 0);
+
+	if (!list_empty(&log->sb_list))
+		goto out;
+
+	/*
+	 * TODO: ensure that the dummy_log is in a state to allow
+	 * lbmLogShutdown to deallocate all the buffers and call
+	 * kfree against dummy_log.  For now, leave dummy_log & its
+	 * buffers in memory, and resuse if another no-integrity mount
+	 * is requested.
+	 */
+	if (log->no_integrity)
+		goto out;
+
+	/*
+	 *	external log as separate logical volume
+	 */
+	list_del(&log->journal_list);
+	bdev = log->bdev;
+	rc = lmLogShutdown(log);
+
+	blkdev_put(bdev, log);
+
+	kfree(log);
+
+      out:
+	mutex_unlock(&jfs_log_mutex);
+	jfs_info("lmLogClose: exit(%d)", rc);
+	return rc;
+}
+
+
+/*
+ * NAME:	jfs_flush_journal()
+ *
+ * FUNCTION:	initiate write of any outstanding transactions to the journal
+ *		and optionally wait until they are all written to disk
+ *
+ *		wait == 0  flush until latest txn is committed, don't wait
+ *		wait == 1  flush until latest txn is committed, wait
+ *		wait > 1   flush until all txn's are complete, wait
+ */
+void jfs_flush_journal(struct jfs_log *log, int wait)
+{
+	int i;
+	struct tblock *target = NULL;
+
+	/* jfs_write_inode may call us during read-only mount */
+	if (!log)
+		return;
+
+	jfs_info("jfs_flush_journal: log:0x%p wait=%d", log, wait);
+
+	LOGGC_LOCK(log);
+
+	if (!list_empty(&log->cqueue)) {
+		/*
+		 * This ensures that we will keep writing to the journal as long
+		 * as there are unwritten commit records
+		 */
+		target = list_entry(log->cqueue.prev, struct tblock, cqueue);
+
+		if (test_bit(log_FLUSH, &log->flag)) {
+			/*
+			 * We're already flushing.
+			 * if flush_tblk is NULL, we are flushing everything,
+			 * so leave it that way.  Otherwise, update it to the
+			 * latest transaction
+			 */
+			if (log->flush_tblk)
+				log->flush_tblk = target;
+		} else {
+			/* Only flush until latest transaction is committed */
+			log->flush_tblk = target;
+			set_bit(log_FLUSH, &log->flag);
+
+			/*
+			 * Initiate I/O on outstanding transactions
+			 */
+			if (!(log->cflag & logGC_PAGEOUT)) {
+				log->cflag |= logGC_PAGEOUT;
+				lmGCwrite(log, 0);
+			}
+		}
+	}
+	if ((wait > 1) || test_bit(log_SYNCBARRIER, &log->flag)) {
+		/* Flush until all activity complete */
+		set_bit(log_FLUSH, &log->flag);
+		log->flush_tblk = NULL;
+	}
+
+	if (wait && target && !(target->flag & tblkGC_COMMITTED)) {
+		DECLARE_WAITQUEUE(__wait, current);
+
+		add_wait_queue(&target->gcwait, &__wait);
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		LOGGC_UNLOCK(log);
+		schedule();
+		LOGGC_LOCK(log);
+		remove_wait_queue(&target->gcwait, &__wait);
+	}
+	LOGGC_UNLOCK(log);
+
+	if (wait < 2)
+		return;
+
+	write_special_inodes(log, filemap_fdatawrite);
+
+	/*
+	 * If there was recent activity, we may need to wait
+	 * for the lazycommit thread to catch up
+	 */
+	if ((!list_empty(&log->cqueue)) || !list_empty(&log->synclist)) {
+		for (i = 0; i < 200; i++) {	/* Too much? */
+			msleep(250);
+			write_special_inodes(log, filemap_fdatawrite);
+			if (list_empty(&log->cqueue) &&
+			    list_empty(&log->synclist))
+				break;
+		}
+	}
+	assert(list_empty(&log->cqueue));
+
+#ifdef CONFIG_JFS_DEBUG
+	if (!list_empty(&log->synclist)) {
+		struct logsyncblk *lp;
+
+		printk(KERN_ERR "jfs_flush_journal: synclist not empty\n");
+		list_for_each_entry(lp, &log->synclist, synclist) {
+			if (lp->xflag & COMMIT_PAGE) {
+				struct metapage *mp = (struct metapage *)lp;
+				print_hex_dump(KERN_ERR, "metapage: ",
+					       DUMP_PREFIX_ADDRESS, 16, 4,
+					       mp, sizeof(struct metapage), 0);
+				print_hex_dump(KERN_ERR, "page: ",
+					       DUMP_PREFIX_ADDRESS, 16,
+					       sizeof(long), mp->page,
+					       sizeof(struct page), 0);
+			} else
+				print_hex_dump(KERN_ERR, "tblock:",
+					       DUMP_PREFIX_ADDRESS, 16, 4,
+					       lp, sizeof(struct tblock), 0);
+		}
+	}
+#else
+	WARN_ON(!list_empty(&log->synclist));
+#endif
+	clear_bit(log_FLUSH, &log->flag);
+}
+
+/*
+ * NAME:	lmLogShutdown()
+ *
+ * FUNCTION:	log shutdown at last LogClose().
+ *
+ *		write log syncpt record.
+ *		update super block to set redone flag to 0.
+ *
+ * PARAMETER:	log	- log inode
+ *
+ * RETURN:	0	- success
+ *
+ * serialization: single last close thread
+ */
+int lmLogShutdown(struct jfs_log * log)
+{
+	int rc;
+	struct lrd lrd;
+	int lsn;
+	struct logsuper *logsuper;
+	struct lbuf *bpsuper;
+	struct lbuf *bp;
+	struct logpage *lp;
+
+	jfs_info("lmLogShutdown: log:0x%p", log);
+
+	jfs_flush_journal(log, 2);
+
+	/*
+	 * write the last SYNCPT record with syncpoint = 0
+	 * (i.e., log redo up to HERE !)
+	 */
+	lrd.logtid = 0;
+	lrd.backchain = 0;
+	lrd.type = cpu_to_le16(LOG_SYNCPT);
+	lrd.length = 0;
+	lrd.log.syncpt.sync = 0;
+
+	lsn = lmWriteRecord(log, NULL, &lrd, NULL);
+	bp = log->bp;
+	lp = (struct logpage *) bp->l_ldata;
+	lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_eor);
+	lbmWrite(log, log->bp, lbmWRITE | lbmRELEASE | lbmSYNC, 0);
+	lbmIOWait(log->bp, lbmFREE);
+	log->bp = NULL;
+
+	/*
+	 * synchronous update log superblock
+	 * mark log state as shutdown cleanly
+	 * (i.e., Log does not need to be replayed).
+	 */
+	if ((rc = lbmRead(log, 1, &bpsuper)))
+		goto out;
+
+	logsuper = (struct logsuper *) bpsuper->l_ldata;
+	logsuper->state = cpu_to_le32(LOGREDONE);
+	logsuper->end = cpu_to_le32(lsn);
+	lbmDirectWrite(log, bpsuper, lbmWRITE | lbmRELEASE | lbmSYNC);
+	rc = lbmIOWait(bpsuper, lbmFREE);
+
+	jfs_info("lmLogShutdown: lsn:0x%x page:%d eor:%d",
+		 lsn, log->page, log->eor);
+
+      out:
+	/*
+	 * shutdown per log i/o
+	 */
+	lbmLogShutdown(log);
+
+	if (rc) {
+		jfs_warn("lmLogShutdown: exit(%d)", rc);
+	}
+	return rc;
+}
+
+
+/*
+ * NAME:	lmLogFileSystem()
+ *
+ * FUNCTION:	insert (<activate> = true)/remove (<activate> = false)
+ *	file system into/from log active file system list.
+ *
+ * PARAMETE:	log	- pointer to logs inode.
+ *		fsdev	- kdev_t of filesystem.
+ *		serial	- pointer to returned log serial number
+ *		activate - insert/remove device from active list.
+ *
+ * RETURN:	0	- success
+ *		errors returned by vms_iowait().
+ */
+static int lmLogFileSystem(struct jfs_log * log, struct jfs_sb_info *sbi,
+			   int activate)
+{
+	int rc = 0;
+	int i;
+	struct logsuper *logsuper;
+	struct lbuf *bpsuper;
+	uuid_t *uuid = &sbi->uuid;
+
+	/*
+	 * insert/remove file system device to log active file system list.
+	 */
+	if ((rc = lbmRead(log, 1, &bpsuper)))
+		return rc;
+
+	logsuper = (struct logsuper *) bpsuper->l_ldata;
+	if (activate) {
+		for (i = 0; i < MAX_ACTIVE; i++)
+			if (uuid_is_null(&logsuper->active[i].uuid)) {
+				uuid_copy(&logsuper->active[i].uuid, uuid);
+				sbi->aggregate = i;
+				break;
+			}
+		if (i == MAX_ACTIVE) {
+			jfs_warn("Too many file systems sharing journal!");
+			lbmFree(bpsuper);
+			return -EMFILE;	/* Is there a better rc? */
+		}
+	} else {
+		for (i = 0; i < MAX_ACTIVE; i++)
+			if (uuid_equal(&logsuper->active[i].uuid, uuid)) {
+				uuid_copy(&logsuper->active[i].uuid,
+					  &uuid_null);
+				break;
+			}
+		if (i == MAX_ACTIVE) {
+			jfs_warn("Somebody stomped on the journal!");
+			lbmFree(bpsuper);
+			return -EIO;
+		}
+
+	}
+
+	/*
+	 * synchronous write log superblock:
+	 *
+	 * write sidestream bypassing write queue:
+	 * at file system mount, log super block is updated for
+	 * activation of the file system before any log record
+	 * (MOUNT record) of the file system, and at file system
+	 * unmount, all meta data for the file system has been
+	 * flushed before log super block is updated for deactivation
+	 * of the file system.
+	 */
+	lbmDirectWrite(log, bpsuper, lbmWRITE | lbmRELEASE | lbmSYNC);
+	rc = lbmIOWait(bpsuper, lbmFREE);
+
+	return rc;
+}
+
+/*
+ *		log buffer manager (lbm)
+ *		------------------------
+ *
+ * special purpose buffer manager supporting log i/o requirements.
+ *
+ * per log write queue:
+ * log pageout occurs in serial order by fifo write queue and
+ * restricting to a single i/o in pregress at any one time.
+ * a circular singly-linked list
+ * (log->wrqueue points to the tail, and buffers are linked via
+ * bp->wrqueue field), and
+ * maintains log page in pageout ot waiting for pageout in serial pageout.
+ */
+
+/*
+ *	lbmLogInit()
+ *
+ * initialize per log I/O setup at lmLogInit()
+ */
+static int lbmLogInit(struct jfs_log * log)
+{				/* log inode */
+	int i;
+	struct lbuf *lbuf;
+
+	jfs_info("lbmLogInit: log:0x%p", log);
+
+	/* initialize current buffer cursor */
+	log->bp = NULL;
+
+	/* initialize log device write queue */
+	log->wqueue = NULL;
+
+	/*
+	 * Each log has its own buffer pages allocated to it.  These are
+	 * not managed by the page cache.  This ensures that a transaction
+	 * writing to the log does not block trying to allocate a page from
+	 * the page cache (for the log).  This would be bad, since page
+	 * allocation waits on the kswapd thread that may be committing inodes
+	 * which would cause log activity.  Was that clear?  I'm trying to
+	 * avoid deadlock here.
+	 */
+	init_waitqueue_head(&log->free_wait);
+
+	log->lbuf_free = NULL;
+
+	for (i = 0; i < LOGPAGES;) {
+		char *buffer;
+		uint offset;
+		struct page *page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+
+		if (!page)
+			goto error;
+		buffer = page_address(page);
+		for (offset = 0; offset < PAGE_SIZE; offset += LOGPSIZE) {
+			lbuf = kmalloc(sizeof(struct lbuf), GFP_KERNEL);
+			if (lbuf == NULL) {
+				if (offset == 0)
+					__free_page(page);
+				goto error;
+			}
+			if (offset) /* we already have one reference */
+				get_page(page);
+			lbuf->l_offset = offset;
+			lbuf->l_ldata = buffer + offset;
+			lbuf->l_page = page;
+			lbuf->l_log = log;
+			init_waitqueue_head(&lbuf->l_ioevent);
+
+			lbuf->l_freelist = log->lbuf_free;
+			log->lbuf_free = lbuf;
+			i++;
+		}
+	}
+
+	return (0);
+
+      error:
+	lbmLogShutdown(log);
+	return -ENOMEM;
+}
+
+
+/*
+ *	lbmLogShutdown()
+ *
+ * finalize per log I/O setup at lmLogShutdown()
+ */
+static void lbmLogShutdown(struct jfs_log * log)
+{
+	struct lbuf *lbuf;
+
+	jfs_info("lbmLogShutdown: log:0x%p", log);
+
+	lbuf = log->lbuf_free;
+	while (lbuf) {
+		struct lbuf *next = lbuf->l_freelist;
+		__free_page(lbuf->l_page);
+		kfree(lbuf);
+		lbuf = next;
+	}
+}
+
+
+/*
+ *	lbmAllocate()
+ *
+ * allocate an empty log buffer
+ */
+static struct lbuf *lbmAllocate(struct jfs_log * log, int pn)
+{
+	struct lbuf *bp;
+	unsigned long flags;
+
+	/*
+	 * recycle from log buffer freelist if any
+	 */
+	LCACHE_LOCK(flags);
+	LCACHE_SLEEP_COND(log->free_wait, (bp = log->lbuf_free), flags);
+	log->lbuf_free = bp->l_freelist;
+	LCACHE_UNLOCK(flags);
+
+	bp->l_flag = 0;
+
+	bp->l_wqnext = NULL;
+	bp->l_freelist = NULL;
+
+	bp->l_pn = pn;
+	bp->l_blkno = log->base + (pn << (L2LOGPSIZE - log->l2bsize));
+	bp->l_ceor = 0;
+
+	return bp;
+}
+
+
+/*
+ *	lbmFree()
+ *
+ * release a log buffer to freelist
+ */
+static void lbmFree(struct lbuf * bp)
+{
+	unsigned long flags;
+
+	LCACHE_LOCK(flags);
+
+	lbmfree(bp);
+
+	LCACHE_UNLOCK(flags);
+}
+
+static void lbmfree(struct lbuf * bp)
+{
+	struct jfs_log *log = bp->l_log;
+
+	assert(bp->l_wqnext == NULL);
+
+	/*
+	 * return the buffer to head of freelist
+	 */
+	bp->l_freelist = log->lbuf_free;
+	log->lbuf_free = bp;
+
+	wake_up(&log->free_wait);
+	return;
+}
+
+
+/*
+ * NAME:	lbmRedrive
+ *
+ * FUNCTION:	add a log buffer to the log redrive list
+ *
+ * PARAMETER:
+ *	bp	- log buffer
+ *
+ * NOTES:
+ *	Takes log_redrive_lock.
+ */
+static inline void lbmRedrive(struct lbuf *bp)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&log_redrive_lock, flags);
+	bp->l_redrive_next = log_redrive_list;
+	log_redrive_list = bp;
+	spin_unlock_irqrestore(&log_redrive_lock, flags);
+
+	wake_up_process(jfsIOthread);
+}
+
+
+/*
+ *	lbmRead()
+ */
+static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
+{
+	struct bio *bio;
+	struct lbuf *bp;
+
+	/*
+	 * allocate a log buffer
+	 */
+	*bpp = bp = lbmAllocate(log, pn);
+	jfs_info("lbmRead: bp:0x%p pn:0x%x", bp, pn);
+
+	bp->l_flag |= lbmREAD;
+
+	bio = bio_alloc(log->bdev, 1, REQ_OP_READ, GFP_NOFS);
+	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
+	__bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
+	BUG_ON(bio->bi_iter.bi_size != LOGPSIZE);
+
+	bio->bi_end_io = lbmIODone;
+	bio->bi_private = bp;
+	/*check if journaling to disk has been disabled*/
+	if (log->no_integrity) {
+		bio->bi_iter.bi_size = 0;
+		lbmIODone(bio);
+	} else {
+		submit_bio(bio);
+	}
+
+	wait_event(bp->l_ioevent, (bp->l_flag != lbmREAD));
+
+	return 0;
+}
+
+
+/*
+ *	lbmWrite()
+ *
+ * buffer at head of pageout queue stays after completion of
+ * partial-page pageout and redriven by explicit initiation of
+ * pageout by caller until full-page pageout is completed and
+ * released.
+ *
+ * device driver i/o done redrives pageout of new buffer at
+ * head of pageout queue when current buffer at head of pageout
+ * queue is released at the completion of its full-page pageout.
+ *
+ * LOGGC_LOCK() serializes lbmWrite() by lmNextPage() and lmGroupCommit().
+ * LCACHE_LOCK() serializes xflag between lbmWrite() and lbmIODone()
+ */
+static void lbmWrite(struct jfs_log * log, struct lbuf * bp, int flag,
+		     int cant_block)
+{
+	struct lbuf *tail;
+	unsigned long flags;
+
+	jfs_info("lbmWrite: bp:0x%p flag:0x%x pn:0x%x", bp, flag, bp->l_pn);
+
+	/* map the logical block address to physical block address */
+	bp->l_blkno =
+	    log->base + (bp->l_pn << (L2LOGPSIZE - log->l2bsize));
+
+	LCACHE_LOCK(flags);		/* disable+lock */
+
+	/*
+	 * initialize buffer for device driver
+	 */
+	bp->l_flag = flag;
+
+	/*
+	 *	insert bp at tail of write queue associated with log
+	 *
+	 * (request is either for bp already/currently at head of queue
+	 * or new bp to be inserted at tail)
+	 */
+	tail = log->wqueue;
+
+	/* is buffer not already on write queue ? */
+	if (bp->l_wqnext == NULL) {
+		/* insert at tail of wqueue */
+		if (tail == NULL) {
+			log->wqueue = bp;
+			bp->l_wqnext = bp;
+		} else {
+			log->wqueue = bp;
+			bp->l_wqnext = tail->l_wqnext;
+			tail->l_wqnext = bp;
+		}
+
+		tail = bp;
+	}
+
+	/* is buffer at head of wqueue and for write ? */
+	if ((bp != tail->l_wqnext) || !(flag & lbmWRITE)) {
+		LCACHE_UNLOCK(flags);	/* unlock+enable */
+		return;
+	}
+
+	LCACHE_UNLOCK(flags);	/* unlock+enable */
+
+	if (cant_block)
+		lbmRedrive(bp);
+	else if (flag & lbmSYNC)
+		lbmStartIO(bp);
+	else {
+		LOGGC_UNLOCK(log);
+		lbmStartIO(bp);
+		LOGGC_LOCK(log);
+	}
+}
+
+
+/*
+ *	lbmDirectWrite()
+ *
+ * initiate pageout bypassing write queue for sidestream
+ * (e.g., log superblock) write;
+ */
+static void lbmDirectWrite(struct jfs_log * log, struct lbuf * bp, int flag)
+{
+	jfs_info("lbmDirectWrite: bp:0x%p flag:0x%x pn:0x%x",
+		 bp, flag, bp->l_pn);
+
+	/*
+	 * initialize buffer for device driver
+	 */
+	bp->l_flag = flag | lbmDIRECT;
+
+	/* map the logical block address to physical block address */
+	bp->l_blkno =
+	    log->base + (bp->l_pn << (L2LOGPSIZE - log->l2bsize));
+
+	/*
+	 *	initiate pageout of the page
+	 */
+	lbmStartIO(bp);
+}
+
+
+/*
+ * NAME:	lbmStartIO()
+ *
+ * FUNCTION:	Interface to DD strategy routine
+ *
+ * RETURN:	none
+ *
+ * serialization: LCACHE_LOCK() is NOT held during log i/o;
+ */
+static void lbmStartIO(struct lbuf * bp)
+{
+	struct bio *bio;
+	struct jfs_log *log = bp->l_log;
+
+	jfs_info("lbmStartIO");
+
+	bio = bio_alloc(log->bdev, 1, REQ_OP_WRITE | REQ_SYNC, GFP_NOFS);
+	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
+	__bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
+	BUG_ON(bio->bi_iter.bi_size != LOGPSIZE);
+
+	bio->bi_end_io = lbmIODone;
+	bio->bi_private = bp;
+
+	/* check if journaling to disk has been disabled */
+	if (log->no_integrity) {
+		bio->bi_iter.bi_size = 0;
+		lbmIODone(bio);
+	} else {
+		submit_bio(bio);
+		INCREMENT(lmStat.submitted);
+	}
+}
+
+
+/*
+ *	lbmIOWait()
+ */
+static int lbmIOWait(struct lbuf * bp, int flag)
+{
+	unsigned long flags;
+	int rc = 0;
+
+	jfs_info("lbmIOWait1: bp:0x%p flag:0x%x:0x%x", bp, bp->l_flag, flag);
+
+	LCACHE_LOCK(flags);		/* disable+lock */
+
+	LCACHE_SLEEP_COND(bp->l_ioevent, (bp->l_flag & lbmDONE), flags);
+
+	rc = (bp->l_flag & lbmERROR) ? -EIO : 0;
+
+	if (flag & lbmFREE)
+		lbmfree(bp);
+
+	LCACHE_UNLOCK(flags);	/* unlock+enable */
+
+	jfs_info("lbmIOWait2: bp:0x%p flag:0x%x:0x%x", bp, bp->l_flag, flag);
+	return rc;
+}
+
+/*
+ *	lbmIODone()
+ *
+ * executed at INTIODONE level
+ */
+static void lbmIODone(struct bio *bio)
+{
+	struct lbuf *bp = bio->bi_private;
+	struct lbuf *nextbp, *tail;
+	struct jfs_log *log;
+	unsigned long flags;
+
+	/*
+	 * get back jfs buffer bound to the i/o buffer
+	 */
+	jfs_info("lbmIODone: bp:0x%p flag:0x%x", bp, bp->l_flag);
+
+	LCACHE_LOCK(flags);		/* disable+lock */
+
+	bp->l_flag |= lbmDONE;
+
+	if (bio->bi_status) {
+		bp->l_flag |= lbmERROR;
+
+		jfs_err("lbmIODone: I/O error in JFS log");
+	}
+
+	bio_put(bio);
+
+	/*
+	 *	pagein completion
+	 */
+	if (bp->l_flag & lbmREAD) {
+		bp->l_flag &= ~lbmREAD;
+
+		LCACHE_UNLOCK(flags);	/* unlock+enable */
+
+		/* wakeup I/O initiator */
+		LCACHE_WAKEUP(&bp->l_ioevent);
+
+		return;
+	}
+
+	/*
+	 *	pageout completion
+	 *
+	 * the bp at the head of write queue has completed pageout.
+	 *
+	 * if single-commit/full-page pageout, remove the current buffer
+	 * from head of pageout queue, and redrive pageout with
+	 * the new buffer at head of pageout queue;
+	 * otherwise, the partial-page pageout buffer stays at
+	 * the head of pageout queue to be redriven for pageout
+	 * by lmGroupCommit() until full-page pageout is completed.
+	 */
+	bp->l_flag &= ~lbmWRITE;
+	INCREMENT(lmStat.pagedone);
+
+	/* update committed lsn */
+	log = bp->l_log;
+	log->clsn = (bp->l_pn << L2LOGPSIZE) + bp->l_ceor;
+
+	if (bp->l_flag & lbmDIRECT) {
+		LCACHE_WAKEUP(&bp->l_ioevent);
+		LCACHE_UNLOCK(flags);
+		return;
+	}
+
+	tail = log->wqueue;
+
+	/* single element queue */
+	if (bp == tail) {
+		/* remove head buffer of full-page pageout
+		 * from log device write queue
+		 */
+		if (bp->l_flag & lbmRELEASE) {
+			log->wqueue = NULL;
+			bp->l_wqnext = NULL;
+		}
+	}
+	/* multi element queue */
+	else {
+		/* remove head buffer of full-page pageout
+		 * from log device write queue
+		 */
+		if (bp->l_flag & lbmRELEASE) {
+			nextbp = tail->l_wqnext = bp->l_wqnext;
+			bp->l_wqnext = NULL;
+
+			/*
+			 * redrive pageout of next page at head of write queue:
+			 * redrive next page without any bound tblk
+			 * (i.e., page w/o any COMMIT records), or
+			 * first page of new group commit which has been
+			 * queued after current page (subsequent pageout
+			 * is performed synchronously, except page without
+			 * any COMMITs) by lmGroupCommit() as indicated
+			 * by lbmWRITE flag;
+			 */
+			if (nextbp->l_flag & lbmWRITE) {
+				/*
+				 * We can't do the I/O at interrupt time.
+				 * The jfsIO thread can do it
+				 */
+				lbmRedrive(nextbp);
+			}
+		}
+	}
+
+	/*
+	 *	synchronous pageout:
+	 *
+	 * buffer has not necessarily been removed from write queue
+	 * (e.g., synchronous write of partial-page with COMMIT):
+	 * leave buffer for i/o initiator to dispose
+	 */
+	if (bp->l_flag & lbmSYNC) {
+		LCACHE_UNLOCK(flags);	/* unlock+enable */
+
+		/* wakeup I/O initiator */
+		LCACHE_WAKEUP(&bp->l_ioevent);
+	}
+
+	/*
+	 *	Group Commit pageout:
+	 */
+	else if (bp->l_flag & lbmGC) {
+		LCACHE_UNLOCK(flags);
+		lmPostGC(bp);
+	}
+
+	/*
+	 *	asynchronous pageout:
+	 *
+	 * buffer must have been removed from write queue:
+	 * insert buffer at head of freelist where it can be recycled
+	 */
+	else {
+		assert(bp->l_flag & lbmRELEASE);
+		assert(bp->l_flag & lbmFREE);
+		lbmfree(bp);
+
+		LCACHE_UNLOCK(flags);	/* unlock+enable */
+	}
+}
+
+int jfsIOWait(void *arg)
+{
+	struct lbuf *bp;
+
+	do {
+		spin_lock_irq(&log_redrive_lock);
+		while ((bp = log_redrive_list)) {
+			log_redrive_list = bp->l_redrive_next;
+			bp->l_redrive_next = NULL;
+			spin_unlock_irq(&log_redrive_lock);
+			lbmStartIO(bp);
+			spin_lock_irq(&log_redrive_lock);
+		}
+
+		if (freezing(current)) {
+			spin_unlock_irq(&log_redrive_lock);
+			try_to_freeze();
+		} else {
+			set_current_state(TASK_INTERRUPTIBLE);
+			spin_unlock_irq(&log_redrive_lock);
+			schedule();
+		}
+	} while (!kthread_should_stop());
+
+	jfs_info("jfsIOWait being killed!");
+	return 0;
+}
+
+/*
+ * NAME:	lmLogFormat()/jfs_logform()
+ *
+ * FUNCTION:	format file system log
+ *
+ * PARAMETERS:
+ *	log	- volume log
+ *	logAddress - start address of log space in FS block
+ *	logSize	- length of log space in FS block;
+ *
+ * RETURN:	0	- success
+ *		-EIO	- i/o error
+ *
+ * XXX: We're synchronously writing one page at a time.  This needs to
+ *	be improved by writing multiple pages at once.
+ */
+int lmLogFormat(struct jfs_log *log, s64 logAddress, int logSize)
+{
+	int rc = -EIO;
+	struct jfs_sb_info *sbi;
+	struct logsuper *logsuper;
+	struct logpage *lp;
+	int lspn;		/* log sequence page number */
+	struct lrd *lrd_ptr;
+	int npages = 0;
+	struct lbuf *bp;
+
+	jfs_info("lmLogFormat: logAddress:%Ld logSize:%d",
+		 (long long)logAddress, logSize);
+
+	sbi = list_entry(log->sb_list.next, struct jfs_sb_info, log_list);
+
+	/* allocate a log buffer */
+	bp = lbmAllocate(log, 1);
+
+	npages = logSize >> sbi->l2nbperpage;
+
+	/*
+	 *	log space:
+	 *
+	 * page 0 - reserved;
+	 * page 1 - log superblock;
+	 * page 2 - log data page: A SYNC log record is written
+	 *	    into this page at logform time;
+	 * pages 3-N - log data page: set to empty log data pages;
+	 */
+	/*
+	 *	init log superblock: log page 1
+	 */
+	logsuper = (struct logsuper *) bp->l_ldata;
+
+	logsuper->magic = cpu_to_le32(LOGMAGIC);
+	logsuper->version = cpu_to_le32(LOGVERSION);
+	logsuper->state = cpu_to_le32(LOGREDONE);
+	logsuper->flag = cpu_to_le32(sbi->mntflag);	/* ? */
+	logsuper->size = cpu_to_le32(npages);
+	logsuper->bsize = cpu_to_le32(sbi->bsize);
+	logsuper->l2bsize = cpu_to_le32(sbi->l2bsize);
+	logsuper->end = cpu_to_le32(2 * LOGPSIZE + LOGPHDRSIZE + LOGRDSIZE);
+
+	bp->l_flag = lbmWRITE | lbmSYNC | lbmDIRECT;
+	bp->l_blkno = logAddress + sbi->nbperpage;
+	lbmStartIO(bp);
+	if ((rc = lbmIOWait(bp, 0)))
+		goto exit;
+
+	/*
+	 *	init pages 2 to npages-1 as log data pages:
+	 *
+	 * log page sequence number (lpsn) initialization:
+	 *
+	 * pn:   0     1     2     3                 n-1
+	 *       +-----+-----+=====+=====+===.....===+=====+
+	 * lspn:             N-1   0     1           N-2
+	 *                   <--- N page circular file ---->
+	 *
+	 * the N (= npages-2) data pages of the log is maintained as
+	 * a circular file for the log records;
+	 * lpsn grows by 1 monotonically as each log page is written
+	 * to the circular file of the log;
+	 * and setLogpage() will not reset the page number even if
+	 * the eor is equal to LOGPHDRSIZE. In order for binary search
+	 * still work in find log end process, we have to simulate the
+	 * log wrap situation at the log format time.
+	 * The 1st log page written will have the highest lpsn. Then
+	 * the succeeding log pages will have ascending order of
+	 * the lspn starting from 0, ... (N-2)
+	 */
+	lp = (struct logpage *) bp->l_ldata;
+	/*
+	 * initialize 1st log page to be written: lpsn = N - 1,
+	 * write a SYNCPT log record is written to this page
+	 */
+	lp->h.page = lp->t.page = cpu_to_le32(npages - 3);
+	lp->h.eor = lp->t.eor = cpu_to_le16(LOGPHDRSIZE + LOGRDSIZE);
+
+	lrd_ptr = (struct lrd *) &lp->data;
+	lrd_ptr->logtid = 0;
+	lrd_ptr->backchain = 0;
+	lrd_ptr->type = cpu_to_le16(LOG_SYNCPT);
+	lrd_ptr->length = 0;
+	lrd_ptr->log.syncpt.sync = 0;
+
+	bp->l_blkno += sbi->nbperpage;
+	bp->l_flag = lbmWRITE | lbmSYNC | lbmDIRECT;
+	lbmStartIO(bp);
+	if ((rc = lbmIOWait(bp, 0)))
+		goto exit;
+
+	/*
+	 *	initialize succeeding log pages: lpsn = 0, 1, ..., (N-2)
+	 */
+	for (lspn = 0; lspn < npages - 3; lspn++) {
+		lp->h.page = lp->t.page = cpu_to_le32(lspn);
+		lp->h.eor = lp->t.eor = cpu_to_le16(LOGPHDRSIZE);
+
+		bp->l_blkno += sbi->nbperpage;
+		bp->l_flag = lbmWRITE | lbmSYNC | lbmDIRECT;
+		lbmStartIO(bp);
+		if ((rc = lbmIOWait(bp, 0)))
+			goto exit;
+	}
+
+	rc = 0;
+exit:
+	/*
+	 *	finalize log
+	 */
+	/* release the buffer */
+	lbmFree(bp);
+
+	return rc;
+}
+
+#ifdef CONFIG_JFS_STATISTICS
+int jfs_lmstats_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m,
+		       "JFS Logmgr stats\n"
+		       "================\n"
+		       "commits = %d\n"
+		       "writes submitted = %d\n"
+		       "writes completed = %d\n"
+		       "full pages submitted = %d\n"
+		       "partial pages submitted = %d\n",
+		       lmStat.commit,
+		       lmStat.submitted,
+		       lmStat.pagedone,
+		       lmStat.full_page,
+		       lmStat.partial_page);
+	return 0;
+}
+#endif /* CONFIG_JFS_STATISTICS */